This invention relates to heating devices and more particularly to a device for attaching modular electronic components to or removing them from a substrate such as a printed circuit board.
Present day devices for removing or installing modular electronic components from a substrate such as a printed circuit board generally fall into two categories: those which use a heated head which contacts each terminal to melt the solder thereon or those which use a blast of hot air to melt the solder. The former devices are generally very complex and employ a heated head having a plurality of spaced apart fingers each of which must be precisely aligned with each terminal around the component to simultaneously heat the solder on it. The component is then withdrawn from the substrate by vacuum suction or other mechanical means. The procedure is reversed for installing a component. An example of such a device is disclosed in U.S. Pat. No. 3,382,564. A major disadvantage of this type of device is that, due to the everincreasing miniaturization of electronic systems and individual components in them, the terminals of such components are extremely close together thus making precise alignment of the fingers of the heating head therewith extremely difficult. Improper alignment or contact often results in solder flowing between terminals on the component thus shorting them or otherwise damaging them. The latter devices direct a blast of hot air at the terminals from a source above the component to simultaneously melt the solder on each. Such a device, for example, is set forth in U.S. Pat. No. 4,366,925. Such a device may function satisfactorily if there is a large spacing between components such that the blast of hot air directed at one component from above will not spill over and melt the solder on the terminals of adjacent components. However, as aforementioned, not only are the components themselves becoming increasingly smaller but their proximity on the printed circuit substrate is also increasing. Thus, there is a need for a device which cannot only provide a closely controlled and evenly distributed source of heat sufficient to melt solder associated with component terminals or printed substrate conductors during installation or removal of the electronic component relative thereto but one which can rapidly and precisely direct this controlled heat where desired thereby minimizing the likelihood of melting the solder on the terminals of adjacent components or otherwise damaging the printed conductors on the substrate. There is also a need for a device of the subject type which has the capability of precisely positioning the electronic component and its terminals on the ends of the printed conductors on the substrate to insure no overlapping as well as removing the component to insure that no liquid solder is smeared on the substrate between the conductors printed thereon.
It is therefore the primary object of the present invention to provide a superior device for installation and removal of electronic components from circuits printed on a substrate.
It is another object of the present invention to provide a device of the subject type which employs a series of stacked nozzles for precisely directing the flow of hot air from a source simultaneously to the solder associated with each component terminal or printed conductor on the substrate.
It is yet another object of the present invention to provide a device wherein the aforementioned nozzles can be both rapidly changed to correspond to the different size of various electronic components as well as moved separately or together to a location to permit cleaning or other preparation of the substrate without shutting off the source of heated air.
It is a further object of the present invention to provide a device which has means for rapidly and accurately positioning the substrate and the electronic component to be installed or removed beneath the source of heated air.
It is a still further object of the present invention to provide a device which has a vacuum means axially aligned with the source of heated air and directing nozzles for positioning the electronic component on or removing it from the substrate.
It is a further object of this invention to provide in a device of the above type, means such as steel wool provided in the heater air passageway to facilitate the transfer of heat to the passing air.
It is a further object of the present invention to provide, in a device of the above-type, a mechanism for efficiently moving a component removal/installation unit between its operative and inoperative positions, this being effected by rotation of the unit through about 90.degree. in a vertical plane such that the initial movement from the printed circuit board is substantially vertical while the final movement to the inoperative position is substantially horizontal.
It is a further object of this invention to provide, in a device of the above-type, improved means for removing a nozzle location device from a heater unit of the above component removal/installation unit.
It is a further object of the present invention to provide, in a device of the above-type, means for maintaining the component removal/installation unit in a substantially vertical alignment as it is rotated between operative and inoperative positions.
It is a further object to provide, in a device of the above-type, means for effectively separating a vacuum device from a semiconductor module upon removal of the vacuum.
It is a further object of this invention to provide a flexible key arrangement for guiding the sliding movement of members with respect to one another such that the need for close tolerances in the key arrangement is avoided.
It is a further object of the present invention to provide, in a device of the above-type, resilient means for biasing a sliding member with respect to a fixed member whereby the need for close tolerances between the latter members is avoided.
It is a further object of the present invention to provide in a device of the above-type, means for accurately positioning a new module to be installed with respect to the component removal/installation device.
It is a further object of this invention to provide, in a device of the above-type, the capability of handling both leadless chip carriers and flat-pac carriers.